In a conventional multicasting method utilizing a transcoder which considers various network environments and types of terminals as illustrated in FIG. 1, a new bitstream with a frame rate, bit rate, and resolution rate corresponding to conditions for communication of an individual terminal using a transcoder embedded in a routing device.
FIG. 1 is a diagram illustrating a conventional multicasting method.
The conventional multicasting method is for maintaining information security and for adopting encryption and decoding.
That is, a compressed video is encrypted, the encrypted video is loaded on a portion of payload of a realtime transport protocol (RTP) packet to be transmitted to a transcoder, a header of the RTP packet is revealed prior to transcoding, the encrypted video data is decoded, and an original video stream is restored.
By transcoding the restored bitstream, a new bitstream with a desired frame rate, bit rate, and resolution rate is generated, and encryption is performed with respect to the generated new bitstream to be transmitted to a client terminal in order to maintain security.
Since transcoding is possible only in case of approaching to contents of a payload of a received packet, sequential operations of encrypting and decoding in a router are necessary resulting in an increase in an amount of calculations and latency, and it is impossible to securely maintain video information since an original bitstream is restored in a router.